14 8 DISCOVERY REPORTS 



The remainder of the specimens have been arranged first in ascending and then 

 descending height of the uterine epithelium. 



Table IX 

 Scheme of the sexual cycle in the female 



FOETUSES 



With the exceptions mentioned the foetuses were measured in dorsal profile in the 

 following manner. A very flexible wire was applied to the mid-dorsal line from the tip 

 of the snout to the end of the tail, and when the wire was straightened out the length 

 thus obtained was recorded as that of the foetus. The exceptions are the following, 

 which were measured with the tape in the field: nos. 472, 508, 509 and 513. Further, 

 the length of the twin foetuses of no. 510 is only approximate since, although I was close 

 at hand and believed them to be sufficiently protected, these embryos were discovered 

 and swallowed by gulls whose enterprise I had underestimated. 



The smallest male pup measured was 80 cm. in length and the smallest female 

 76 cm. ; the latter had a length of fresh umbilical cord still attached. 



Note on pregnant uteri. In pregnancy the foetus and all its membranes are confined 

 to one cornu, which is almost invariably that belonging to the ovary containing an active 

 corpus luteum, but in seal no. 436 the corpus luteum of pregnancy was that in the ovary 

 opposite the pregnant cornu and the corpus on the pregnant side was degenerate, it 

 follows that the ovum must have passed from one cornu to the other. Fig. 6 is based 

 on a field sketch of the uterus of no. 531 and shows clearly that pregnancy is entirely 

 confined to one horn. 



CHANGES IN THE STERILE CORNU OF THE PREGNANT UTERUS 

 In the earlier part of pregnancy the sterile cornu presents an appearance closely 

 resembling that of the post-ovulation uterus, but about this time a regression begins 



